Gas turbines generally operate by combusting a fuel and air mixture in one or more combustors to create a high-energy combustion gas that passes through a turbine, thereby causing a turbine rotor shaft to rotate. The rotational energy of the rotor shaft may be converted to electrical energy via a generator coupled to the rotor shaft. Each combustor generally includes fuel nozzles that provide for premixing of the fuel and air upstream of a combustion zone, as a means to keep nitrogen oxide (NOx) emissions low.
Gaseous fuels, such as natural gas, often are employed as a combustible fluid in gas turbine engines used to generate electricity. In some instances, it may be desirable for the combustion system to be able to combust liquid fuels, such as distillate oil. In some configurations, liquid fuel may be provided to an annular fuel manifold and may circulate through the annular fuel manifold, e.g., along a circumference of the annular fuel manifold. Liquid fuel flowing through the various portions of a fuel nozzle may be exposed to relatively high temperatures. So long as the liquid fuel moves quickly enough through the fuel nozzle, the liquid fuel may provide advantageous cooling to the fuel system. However, if the liquid fuel moves too slowly and/or becomes stagnant, the high temperatures may adversely affect the liquid fuel.